Antistatic belts

ABSTRACT

The invention relates to belts made of thermoplastic polymer (A) and comprising a sufficient amount of a polymer (B) to render them antistatic, the said polymer (B) comprising polyethylene glycol blocks. Use is advantageously made of polymers (A) containing polyamide-6 (PA-6) or polyamide-12 (PA-12) blocks and polytetramethylene glycol blocks and polymers (B) containing PA-6 or PA-12 blocks and polyethylene glycol blocks.

This is a continuation of application Ser. No. 08/775,680, filed Dec.23, 1996 now U.S. Pat. No. 5,830,983.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to antistatic belts. In particular, itrelates to power transmission belts and conveyor belts.

2. Description of Related Art

The friction of power transmission belts and conveyer belts on thepulleys, the drive rollers or the rollers to be driven causes staticelectricity which can damage electronic mechanisms or articlestransported by the belt. The majority of belts made of rubber or ofthermoplastic polymer can be rendered antistatic by the incorporation ofcarbon black, of conductive plasticizers and of additives such asquaternary ammonium salts or ethoxylated derivatives.

These incorporated products migrate in the polymer or the rubber andexude, which weakens or destroys the antistatic effect. As for carbonblack, in particular, its color is sometimes unacceptable. It is alsopossible to incorporate conductive fibers in the belt, which isoptionally in woven form, but it is necessary to use adhesives.Moreover, the mechanical properties are sometimes very different fromthe material of the belt, which can result in breakages or losses inantistatic behavior.

SUMMARY OF THE INVENTION

It has now been discovered that it is possible to make belts fromthermoplastic polymer (A) comprising a polymer (B) comprisingpolyethylene glycol blocks in an amount sufficient to render the beltsantistatic.

Within the meaning of the invention, the term "belts" is understood toimply both power transmission belts, which can be flat, or "v"-shaped,trapezoidal or even circular in cross-section, and conveyor belts. Thesaid conveyor belts can be, for example, from 0.2 to 1.5 m wide, for thetransportation of articles, and bands from 1 to 5 cm wide for readingmagnetic tickets or cards.

The thermoplastic polymer (A) is any polymer having mechanicalcharacteristics which are satisfactory for making a belt, that is tosay, having size stability at small elongations while having good stressat these small elongations. Moreover, the thermoplastic polymer must beinsensitive to moisture, in order for its mechanical properties to beindependent of ambient moisture. Suitable examples of polymer (A),includes:

styrene/butadiene/styrene (SBS) block copolymers;

styrene/ethylene-butene/styrene (SEBS) block copolymers;

styrene/isoprene/styrene (SIS) copolymers;

EPDMs (ethylene-propylene-diene);

ethylene-propylene rubbers (EPR);

polyamides or mixtures of polyamides and polyolefins with a polyamidematrix;

polyurethane elastomers (TPU);

polyetherester elastomers;

polymers containing polyamide blocks and polyether blocks.

The term "polyamide" is understood to mean the condensation products:

of one or a number of amino acids, such as aminocaproic,7-aminoheptanoic, 11-aminoundecanoic and 12-aminododecanoic acids, or ofone or a number of lactams, such as caprolactam, oenantholactam andlauryllactam;

of one or a number of salts or mixtures of diamines, such ashexamethylenediamine, dodecamethylenediamine, meta-xylylenediamine,bis-(p-aminocyclohexyl)methane and trimethylhexamethylene-diamine, withdiacids, such as isophthalic, terephthalic, adipic, azelaic, suberic,sebacic and dodecanedicarboxylic acids;

or mixtures of some of these monomers, which results in copolyamides.

Polyamide mixtures can be used. Use is advantageously made of nylon-6(PA-6), nylon-6,6 (PA-6,6) and nylon-12 (PA-12).

As regards mixtures of polyamide and polyolefins with a polyamidematrix, the term "polyolefins" is understood to mean polymers comprisingolefin units such as, for example, ethylene, propylene or 1-buteneunits, and the like.

Mention may be made, by way of example, of:

polyethylene, polypropylene or copolymers of ethylene with α-olefins, itbeing possible for these products to be grafted with unsaturatedcarboxylic acid anhydrides, such as maleic anhydride, or unsaturatedepoxides, such as glycidyl methacrylate,

copolymers of ethylene with at least one product chosen from (i)unsaturated carboxylic acids, their salts or their esters, (ii) vinylesters of saturated carboxylic acids, (iii) unsaturated dicarboxylicacids, their salts, their esters, their monoesters or their anhydrides,or (iv) unsaturated epoxides, it being possible for these ethylenecopolymers to be grafted with unsaturated dicarboxylic acid anhydridesor saturated epoxides,

styrene/ethylene-butene/styrene (SEBS) block copolymers which areoptionally maleized.

Mixtures of two or a number of these polyolefins can be used.

Use is advantageously made of:

polyethylene,

copolymers of ethylene and an α-olefin,

ethylene/alkyl (meth)acrylate copolymers,

ethylene/alkyl (meth)acrylate/maleic anhydride copolymers, the maleicanhydride being grafted or copolymerized,

ethylene/alkyl (meth)acrylate/glycidyl methacrylate copolymers, theglycidyl methacrylate being grafted or copolymerized, and

polypropylene.

It is advantageous, in order to facilitate the formation of thepolyamide matrix, if the polyolefins have few or no functional groupswhich can facilitate compatibilization, to add a compatibilizing agent.

The compatibilizing agent is a product known per se for compatibilizingpolyamides and polyolefins.

Mention may be made, for example, of:

polyethylene, polypropylene, ethylene-propylene copolymers orethylene-butene copolymers, all these products being grafted with maleicanhydride or glycidyl methacrylate,

ethylene/alkyl (meth)acrylate/maleic anhydride copolymers, the maleicanhydride being grafted or copolymerized,

ethylene/vinyl acetate/maleic anhydride copolymers, the maleic anhydridebeing grafted or copolymerized,

the two preceding copolymers in which maleic anhydride is replaced byglycidyl methacrylate,

ethylene/(meth)acrylic acid copolymers or optionally their salts,

polyethylene, propylene or ethylene-propylene copolymers, these polymersbeing grafted with a product exhibiting a site which reacts with amines,these grafted copolymers then being condensed with polyamides orpolyamide oligomers having a single amine end group.

These products are described in Patents FR 2,291,225 and EP 342,066, thecontents of which are incorporated herein by reference.

The amount of polyamide forming the matrix can be between 55 and 95parts by weight per 5 to 45 parts by weight of polyolefins.

The compatibilizing agent is used in an amount sufficient for thepolyolefin to disperse in the form of nodules in the polyamide matrix.It can represent up to 20% of the weight of the polyolefin. Theseproducts are manufactured by mixing polyamide, polyolefin and,optionally, compatibilizing agent according to the usual techniques formixing in the molten state (twin-screw, Buss, single-screw).

The polyurethane elastomers result from the sequence containing thefollowing three (3) base units:

1) a linear polyol with OH endings with a molar mass, for example, of500 to 3,500. The polyols can be chosen either from polyesters, such asadipates, azelates, isophthalates and polycaprolactone, or frompolyethers, such as polypropylene glycol (PPG) or polytetramethyleneglycol (PTMG),

2) a diisocyanate which can be aromatic, such as diphenylmethane4,4'-diisocyanate (MDI) or toluene 2,4-diisocyanate (TDI) ornonaromatic, such as dicyclohexylmethane 4,4'-diisocyanate,

3) a low molecular weight glycol, such as 1,4-butanediol, ethyleneglycol or 1,4-phenylene bis(β-hydroxyethyl) ether, as chain extender.

The sequences containing (1) and (2) form the flexible segments of thepolyurethane and the sequences containing (1) and (3) form the rigidsegments.

The polyetheresters comprise the following units:

1) dicarboxylic acids, such as terephthalic acid or2,6-naphthalenedicarboxylic acid;

2) polyetherdiols, such as polypropylene glycol or polytetramethyleneglycol;

3) a low molecular weight glycol, such as 1,4-butanediol or ethyleneglycol.

The sequences containing (1) and (2) form the flexible segments of thepolyetherester and the sequences containing (1) and (3) form the rigidsegments thereof.

These products are described in Patents EP 402,883 and EP 405,227.

The polymers containing polyamide blocks and polyether blocks resultfrom the copolycondensation of polyamide sequences containing reactiveends with polyether sequences containing reactive ends, such as, interalia:

1) Polyamide sequences containing diamine chain ends withpolyoxyalkylene sequences containing dicarboxyl chain ends,

2) Polyamide sequences containing dicarboxyl chain ends withpolyoxyalkylene sequences containing diamine chain ends obtained bycyanoethylation and hydrogenation of α,ω-dihydroxylated aliphaticpolyoxyalkylene sequences, known as polyetherdiols,

3) Polyamide sequences containing dicarboxyl chain ends withpolyetherdiols, the products obtained being, in this specific case,polyetheresteramides.

The polyamide sequences containing dicarboxyl chain ends result, forexample, from the condensation of α,ω-aminocarboxylic acids from lactamsor from dicarboxylic acids and diamines in the presence of achain-limiting dicarboxylic acid. The polyamide blocks areadvantageously formed from polyamide-12 or from polyamide-6.

The number-average molar mass Mn of the polyamide sequences is between300 and 15,000 and preferably between 600 and 5,000. The Mn mass of thepolyether sequences is between 100 and 6,000 and preferably between 200and 3,000.

The polymers containing polyamide blocks and polyether blocks can alsocomprise units distributed randomly. These polymers can be prepared bythe simultaneous reaction of the polyether and the precursors of thepolyamide blocks.

For example, polyetherdiol, a lactam (or an α,ω-amino acid) and achain-limiting diacid can be reacted in the presence of a small amountof water. A polymer is obtained having essentially polyether blocks andpolyamide blocks of highly variable length but also the variousreactants, which have reacted randomly, distributed statistically alongthe polymer chain.

These polymers contain polyamide blocks and polyether blocks, whetherthey originate from the copolycondensation of polyamide and polyethersequences prepared beforehand or from a single-stage reaction, exhibit,for example, Shore D hardnesses which can be between 30 and 75 andadvantageously between 30 and 70 and an intrinsic viscosity between 0.8and 2.5, measured in metacresol at 250° C. for an initial concentrationof 0.8 g/100 ml.

Whether the polyether blocks derive from polypropylene glycol or frompolytetramethylene glycol, they are either used as they are andcopolycondensed with polyamide blocks containing carboxyl ends or theyare aminated in order to convert the polyetherdiamines and thencondensed with polyamide blocks containing carboxyl ends. They can alsobe mixed with polyamide precursors and a chain limiter in order toprepare polymers containing polyamide blocks and polyether blocks havingunits distributed statistically.

Polymers containing polyamide blocks and polyether blocks are describedin U.S. Pat. Nos. 4,331,786; 4,115,475; 4,195,015; 4,839,441; 4,864,014;4,230,838 and 4,332,920.

The polyether can be, for example, a polypropylene glycol (PPG) or apolytetramethylene glycol (PTMG). The latter is also known aspolytetrahydrofuran (PTHF).

When the polyether blocks are in the chain of the polymer containingpolyamide blocks and polyether blocks in the form of diols or diamines,they are known for simplicity as PPG blocks or PTMG blocks. This polymercontaining polyamide blocks and polyether blocks can comprise a numberof types of polyamide blocks and/or a number of types of polyetherblocks in the same chain.

The polymer containing polyamide blocks and polyether blocks preferablycomprises a single type of polyamide block and a single type ofpolyether block. Use is advantageously made of polymers containing PA-12blocks and PTMG blocks and polymers containing PA-6 blocks and PTMGblocks.

It is also possible to use a mixture of these two polymers containingpolyamide blocks and polyether blocks.

According to another form of the invention, the polymer containingpolyamide blocks and polyether blocks is such that the polyamide is themajor constituent by weight, that is to say, the amount of polyamidewhich is in the form of blocks and that which is optionally distributedstatistically in the chain represents 50% by weight or more of thepolymer containing polyamide blocks and polyether blocks.Advantageously, the amount of polyamide and the amount of polyether arein the ratio (polyamide/polyether) of 1/1 to 4/1.

Advantageously, (A) is selected from polyamides, copolymers containingpolyamide blocks and polyether blocks, polyurethane elastomers orpolyetheresters.

Preferably, (A) is a polyamide-6, a polyamide-11, a polyamide-12, apolymer containing PA-6 blocks and PTMG blocks or a polymer containingPA-12 blocks and PTMG blocks.

The polyethylene glycol (or polyoxyethylene, PEG) blocks, HO-- [--C₂ H₄--O--]_(n) --H, of the polymer (B) can have an Mn mass between 200 and6,000.

The polymer (B) can be, for example:

a polyurethane elastomer in which the polyol (1) is polyethylene glycol,

a polyetherester in which the polyetherdiol (2) is polyethylene glycol,

a polymer containing polyamide blocks and polyether blocks in which thepolyether is polyethylene glycol.

Advantageously, the polymer (B) is a polymer containing polyamide blocksand polyethylene glycol blocks. The polyamide blocks are preferablyformed from PA-6 or from PA-12.

According to another form of the invention, the polymer (A) can contain,in its chain, PEG blocks in addition to other polyether blocks. If theamount of PEG is sufficient, then the presence of (B) is not necessary.

The belts of the invention are considered to be antistatic when thehalf-discharge time is less than 3 seconds, advantageously less than 1second, and preferably between 0.2 and 0.7 seconds.

The half-discharge time is measured as follows:

A sample is placed on an electrically grounded rotating plate. Anelectrode is positioned out of contact above the sample and is broughtto 10 kvolts. This causes ionization of the air and the deposition ofcharges on the sample.

Another, diametrically opposite electrode measures the surfacepotential. When the surface potential reaches a steady-state value, thismeans that charges are flowing out as fast as they are deposited.Charging is halted and then the time taken for the surface potential tofall to half the steady-state value is measured. This time is known asthe half-discharge time.

Another test is also used as follows: a belt of the invention or a plateor a bar produced from the material of the belts of the invention isrubbed for a long time with a woollen rag. It does not attract cigaretteash, whereas the polymer (A) alone attracts this ash.

It has been discovered that these tests corresponded to an antistaticbehavior, whereas the conventional measurement of the surfaceresistivity, which falls by a factor of 100 to 1,000 between thepolymers (A) and the compositions of the invention comprising thepolymers (A) and (B), remains at high values.

The amount of (B) depends on its PEG content and on the antistaticeffect desired. Antistatic behavior increases with the amount of (B) andthe amount of PEG. The amount of (B) can be from 10 to 40% by weight of(A)+(B).

These mixtures of (A) and (B) can be manufactured according to the usualtechniques for mixing thermoplastics in the molten state (twin-screw,Buss, single-screw).

The mixture of (A) and (B) can also comprise antioxidants, agents forcombating UV radiation, fillers, and the like.

The advantage of the belts of the invention is their permanentantistatic behavior; there is no migration of (B). If (A) and (B) arepolymers containing polyamide blocks and polyether blocks and if the PAblocks of (A) and (B) are of the same type, then the mixture of (A) and(B) is transparent. The belts of the invention do not stain and are notgreasy. Another advantage is that the belts of the invention can bewashed or wiped without risk of removing the product which contributesthe antistatic behavior, unlike ordinary antistatics, which exude,causing a fall in the antistatic behavior.

The belts of the invention are advantageously such that (A) is a polymercontaining PA-12 or PA-6 blocks and PTMG blocks and (B) is a polymercontaining PA-6 blocks and PEG blocks or containing PA-12 blocks and PEGblocks or their mixture; the belts are preferably such that (A) is apolymer containing PA-6 blocks and PTMG blocks and (B) is a polymercontaining PA-6 blocks and PEG blocks or such that (A) is a polymercontaining PA-12 blocks and PTMG blocks and (B) is a polymer containingPA-12 blocks and PEG blocks.

The invention also relates to belts comprising a core made of a material(C) between two layers of the antistatic mixture of (A) and (B)described above.

The material (C) can be defined as any material possessing themechanical properties which are satisfactory for making a belttherefrom, both of the power transmission belt and conveyor belt type.Advantageously, (C) is made of polymer (A).

These belts can be produced by coextrusion. A coextrusion binder oradhesive can optionally be deposited between the core (C) and eachantistatic layer. It is also possible to deposit, by extrusion, the twoantistatic layers on the core (C) or to laminate all these layers or anycombination of these possibilities. The adhesive can be a hot melt.

Mention may be made, as examples of binders, of:

polyethylene, polypropylene, copolymers of ethylene and at least oneα-olefin, or mixtures of these polymers, all these polymers beinggrafted with unsaturated carboxylic anhydrides, such as, for example,maleic anhydride. It is also possible to use mixtures of these graftedpolymers and of these nongrafted polymers,

copolymers of ethylene with at least one product chosen from (i)unsaturated carboxylic acids, their salts or their esters, (ii) vinylesters of saturated carboxylic acids, (iii) unsaturated dicarboxylicacids, their salts, their esters, their monoesters or their anhydrides,or (iv) unsaturated epoxides, it being possible for these copolymers tobe grafted with unsaturated dicarboxylic anhydrides, such as maleicanhydride, or unsaturated epoxides, such as glycidyl methacrylate,

polymers containing polyamide blocks and polyether blocks.

Use is advantageously made of structures requiring neither adhesive norbinder. Mention may be made, by way of examples, of:

(A) and (C) as polyetherester,

(A) and (C) as polyamide,

(C) as polyamide and (A) as polymer containing polyamide blocks andpolyether blocks,

(C) and (A) as polymer containing polyamide blocks and polyether blocks,

(C) and (A) as polyurethane elastomer,--(C) as polyurethane elastomerand (A) as polymer containing polyamide blocks and polyether blocks orvice versa.

Preference is given to the structure such that:

(C) is a polymer containing PA-12 blocks and PTMG blocks or apolyamide-12,

(A) is a polymer containing PA-12 blocks and PTMG blocks,

(B) is a polymer containing PA-6 blocks and PEG blocks or a polymercontaining PA-12 blocks and PEG blocks or their mixture.

According to another form of the invention, the core (C) is completelycovered with the antistatic mixture of (A) and (B), that is to say that,in a cross-section of the belt, the core is completely surrounded by theantistatic mixture of (A) and (B).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following examples:

Pebax 1 denotes: a polymer (A) having PA-12 blocks and PTMG blocks withmasses of Mn 2000 and 2000 respectively; the MFI (melt flow index)according to ASTM D12 38 is 5 (235° C., 1 kg), the melting temperature168° C. and the Shore D hardness 40,

Pebax 2 denotes: a polymer (B) having PA-12 blocks and PEG blocks withmasses of Mn 1500 and Mn 1500 respectively; the melting temperature is158° C. and the Shore D hardness 40,

Pebax 3 denotes: a polymer (B) having PA-6 blocks and PEG blocks withmasses of Mn 1500 and Mn 1500 respectively; the melting temperature is204° C. and the Shore D hardness 40.

The compositions which appear in Table 1 were prepared by compounding.

They are put into the form of bars, films and plates in order to measurethe properties thereof. Flat belts with a width of 20 cm and a thicknessof 0.9 cm were subsequently prepared in the material of Examples 4 and7.

The tensile properties of plates were measured on samples of I.F.C.standards (Institut Francais Du Caoutchovc)

The results appear in Table 2, in which "s" means the standarddeviation.

                                              TABLE 1                         

    ______________________________________                                        Examples 1      2       3    4     5    6     7                               ______________________________________                                        Pebax 1  100    90      80   60    90   80    60                                Polymer                                                                       (A)                                                                           Pebax 2             10   20    40                                             Polymer                                                                       (B)                                                                           Pebax 3   10   20      40                                                     Polymer                                                                       (B)                                                                           Σ (parts by           100  100   100   100  100     100 100                                                          weight)                        ______________________________________                                                                                                        TABLE     

    __________________________________________________________________________                                                  2                               Tensile test on I.F.C. test specimens cut out from films in the direction     parallel to extr.                                                                Examples                                                                               Unit                                                                           1       2       4       5       6       7                        __________________________________________________________________________    TENSILE TEST                                                                    Stress at 5%      MPa    3.95 s =    0.16  4.37 s =   0.32  4.67 s =                                                                  0.16  3.81 s =                                                                 0.17  4.05 s =                                                                 0.09   3.77 s                                                               =   0.34                                                                       Stress at 10%                                                                   MPa    5.84                                                                s =   0.03                                                                    6.07 s =   0.18                                                                6.25 s =                                                                     0.06   5.53 s =                                                                 0.06  5.79 s                                                                =   0.11  5.43                                                                s =   0.20                                                                     Stress at 15%                                                                   MPa    6.93                                                                s =   0.03                                                                    7.09 s =   0.16                                                                7.23 s =                                                                     0.08   6.59 s =                                                                 0.02  6.83 s                                                                =   0.12  6.43                                                                s =   0.18                                                                     Stress at 25%                                                                   MPa    8.04                                                                s =   0.01                                                                    8.27 s =   0.22                                                                8.51 s =                                                                     0.09   7.75 s =                                                                 0.01  8.06 s                                                                =   0.14   7.68                                                               s =   0.14                                                                     Stress at 50%                                                                   MPa    9.11                                                                s =   0.05 9.35                                                               s =   0.30                                                                    9.75 s =   0.13                                                                8.78 s =                                                                     0.04 9.21 s =                                                                 0.15   8.89 s =                                                                 0.10                Stress at 100%    MPa    9.92 s =   0.05 10.10 s =   0.34 10.55 s =                                                                   0.13   9.56 s =                                                                 0.09  10.07 s                                                               =   0.18  9.69                                                                s =   0.12                                                                     Stress at 200%                                                                  MPa   11.94                                                                s =   0.07                                                                    11.91  s =                                                                    0.29 12.22 s =                                                                 0.20 11.37 s =                                                                 0.06 11.97 s                                                                =    0.24 11.24                                                               s =   0.09                                                                     Stress at 300%                                                                  MPa   14.62                                                                s =   0.13                                                                    14.37 s =                                                                     0.20 14.49 s =                                                                 0.27 13.92 s =                                                                 0.03 14.37 s                                                                =   0.36 13.56                                                                s =   0.14                                                                     Stress at                                                                       MPa    46.4                                                                s =   0.5                                                                     42.7 s =   3.3                                                                 40.9 s =   1.2                                                                  37.0 s =                                                                   2.4   34.7 s =                                                                 2.4   29.3 s =                                                                 2.2                 break                                                                         Elongation at %             814 s =   7      798 s =   12      834 s =                                                                 8      731 s =                                                                 28     757 s                                                                =   3      703                                                                s =   46                                                                       break              __________________________________________________________________________

The half-discharge times and the surface resistivity were measured, thesamples having been stored for 15 days in an atmosphere at 230° C. witha relative humidity of 50% (50% RH).

The measurements were also repeated two months later, in order todetermine the effect of the humidity. These results are given in Table3.

                                             TABLE 3                          

    ______________________________________                                                             Half-discharge time                                                           Surface resistivity (Ω)                              (sec)               ASTM D 257                                              Examples  Initial + 2 months Initial                                                                              + 2 months                                ______________________________________                                        1         3.5     2.3        3.8 × 10.sup.14                                                                9.5 × 10.sup.13                       2         0.5         0.6     2.7 × 10.sup.12  2.5 ×                                                10.sup.12                                   3         0.7                  1.4 × 10.sup.12                          4         0.2         0.3     6.3 × 10.sup.11 3.8 ×                                                 10.sup.11                                   5         0.5         0.7     4.5 × 10.sup.12  9.7 ×                                                10.sup.12                                   6         0.5         0.5     1.3 × 10.sup.12  4.1 ×                                                10.sup.12                                   7         0.6         0.4     2.3 × 10.sup.11                         ______________________________________                                    

It has also been observed that Samples 2 to 7, rubbed with a woollencloth, do not attract cigarette ash whereas Sample 1, under the sameconditions, does attract it.

What is claimed is:
 1. A belt comprising a thermoplastic polymer (A) and further comprising a sufficient amount of a polymer (B) to render it antistatic, wherein polymer (B) comprises polyethylene glycol blocks and wherein the thermoplastic polymer (A) comprises at least one polymer selected from the group consisting of a polyamide, a mixture comprising at least one polyamide present in the form of a matrix and at least one polyolefin, and a copolymer comprising polyamide blocks and polyether blocks wherein the polyether blocks are selected from the group consisting of polypropylene glycol, polytetramethylene glycol, and mixtures thereof.
 2. The belt according to claim 1, wherein the thermoplastic polymer (A) is at least one polymer selected from the group consisting of polyamides and copolymers comprising polyamide blocks and polyether blocks wherein the polyether blocks are selected from the group consisting of polypropylene glycol, polytetramethylene glycol, and mixtures thereof.
 3. The belt according to claim 2, wherein the thermoplastic polymer (A) is at least one polymer selected from the group consisting of polyamide-6, polyamide-11, polyamide-12, copolymers comprising polyamide-6 blocks and polytetramethylene glycol blocks, copolymers containing polyamide-11 blocks and polytetramethylene glycol blocks, and copolymers containing PA-12 blocks and polytetramethylene glycol blocks.
 4. The belt according to claim 1, wherein the polymer (B) is at least one polymer selected from the group consisting of polyurethane elastomers wherein the polyol of the flexible segments is polyethylene glycol, polyetheresters wherein the polyol of the flexible segments is polyethylene glycol, and copolymers comprising polyamide blocks and polyethylene glycol blocks.
 5. The belt according to claim 4, wherein the polymer (B) is selected from copolymers comprising polyamide blocks and polyethylene glycol blocks, the polyamide blocks comprising polyamide-6 or polyamide-12.
 6. The belt according to claim 1, wherein polymer (B) represents 10 to 40% by weight of (A)+(B).
 7. The belt according to claim 1, further comprising a core comprising a material (C), wherein the core is interposed between two antistatic layers, each layer comprising an antistatic mixture of thermoplastic polymer (A) and polymer (B).
 8. The belt according to claim 1, used as a power transmission belt or as a conveyor belt.
 9. The belt according to claim 7, wherein the material (C) comprises the thermoplastic polymer (A).
 10. A belt comprising a thermoplastic polymer (A) and further comprising a sufficient amount of a polymer (B) to render it antistatic, wherein polymer (B) comprises polyethylene glycol blocks and wherein the thermoplastic polymer (A) comprises at least one copolymer comprising polyamide blocks and polyether blocks wherein the polyether blocks are selected from the group consisting of polypropylene glycol, polytetramethylene glycol, and mixtures thereof.
 11. The belt according to claim 10, wherein the thermoplastic polymer (A) comprises at least one copolymer comprising polyamide blocks and polyether blocks and further wherein the polyether blocks comprise polytetramethylene glycol and the polyamide blocks comprise polyamide-6 or polyamide-12.
 12. The belt according to claim 11, wherein the polymer (B) is selected from copolymers comprising polyamide blocks and polyethylene glycol blocks, the polyamide blocks comprising polyamide-6 or polyamide-12.
 13. The belt according to claim 12, wherein the polymer (B) represents 10 to 40% by weight of (A)+(B).
 14. The belt according to claim 12, further comprising a core comprising a material (C), wherein the core is interposed between two antistatic layers, each layer comprising an antistatic mixture of thermoplastic polymer (A) and polymer (B).
 15. The belt according to claim 14, wherein the material (C) comprises the thermoplastic polymer (A).
 16. The belt according to claim 12, used as a power transmission belt or as a conveyor belt. 